The goal of the University of Chicago Cancer Research Center (UCCRC) Animal Barrier Facilities is to provide Cancer Center members the ability to conduct studies with rodents free of intercurrent infection with adventitious murine pathogens. The Barriers are supported by the facilities, programs, and staff of the University's Animal Resources Center (ARC). The ARC's Comparative Diagnostic Laboratory(CDL) provides expertise in rodent serology, microbiology, parasitology, and hematology. All biological materials introduced into rodents maintained in these facilities are evaluated by the CDL for contamination with adventitious viruses and mycoplasma by MAP testing. The ARC conducts an extensive Murine Health Monitoring Program to confirm that the pathogen-free status of the barrier colonies are maintained. The program is designed to detect variance in health status at specific time intervals. The program employs sentinel animals monitored monthly, serum banking, evaluation of "index" cases and close communication with investigative staff who may note unexplained variances in their experiments. Additionally, a quarantine program which includes extensive diagnostic evaluation is instituted for all rodents imported from colonies obtained from non-commercial vendors. Quarantine is essential to minimize the likelihood of introducing unwanted murine pathogens into barrier colonies. The rodent barrier facilities serving the UCCRC are located on the top floor of the Franklin McLean Institute (FMI) and in the basement of Biological Sciences Learning Center (BSLC). They are essential components of the Cancer Research Center, providing approximately 7,925 net square feet of animal holding and procedure space. The facilities contain sixteen animal holding rooms, seven of which are equipped with three Illinois cubicles. In addition to animal holding rooms, the barriers are equipped with laboratory and procedure space. Isolator type caging systems are employed throughout the barriers. All caging materials and feed are autoclaved prior to use. Animals are transferred within a separate hood or within a cubicle by animal care specialists, using chemically disinfected forceps between cage transfers. A maximum of four or five mice, dependent on weight, are permitted per cage. A bar coded cage card provides encrypted information including the strain or stock, source, and investigator. Cage cards are routinely scanned for information which is downloaded into the ARC database that is used to maintain accurate and detailed census information.